#What is the pathology?#

The epidermis alone is involved; it consists, in fact, of a hyperplasia
of the horny layer.

#State the prognosis of callositas.#

If the causes are removed, the accumulation, as a rule, gradually
disappears. The effect of treatment is always rapid and positive, but
unless the etiological factors have ceased to act, the result is usually
but temporary.

#How is callositas treated?#

When treatment is deemed advisable, it consists in softening the parts
with hot-water soakings or poultices, and subsequently shaving or
scraping off the callous mass. The same result may also be often
effected by the continuous application, for several days or a week, of a
10 to 15 per cent. salicylated plaster, or the application of a
salicylated collodion, same strength; it is followed up by hot-water
soaking, the accumulation, as a rule, coming readily away.

#Clavus.#
(_Synonym:_ Corn.)

#What is clavus?#

Clavus, or corn, is a small, circumscribed, flattened, deep-seated,
horny formation usually seated about the toes.

#Describe the clinical appearances.#

Ordinarily a corn has the appearance of a small callosity; the skin is
thickened, polished and horny. Exceptionally, however, occurring on
parts that are naturally more or less moist, as between the toes,
maceration takes place, and the result is the so-called _soft corn_. The
dorsal aspect of the toes is the common site for the ordinary variety.
The usual size is that of a small pea. They are painful on pressure,
and, at times, spontaneously so.

#State the causes.#

Corns are caused by pressure and friction, and may usually be referred
to improperly fitting shoes.

#What is the pathology of clavus?#

It is a hypertrophy of the epiderm. Its shape is conical, with the base
external and the apex pressing upon the papillae. It is, in fact, a
peculiarly-shaped callosity, the central portion and apex being dense
and horny, forming the so-called core.

#Give the treatment of clavus.#

A simple method of treatment consists in shaving off, after a
preliminary hot-water soaking, the outer portion, and then applying a
ring of felt or like material, with the hollow part immediately over the
site of the core; this should be worn for several weeks. It is also
possible in some cases to extract the whole corn by gently dissecting it
out; the after-treatment being the same as t